In recent years, advances in semiconductor manufacturing technology have been striking, and there have been great demands for hyperfine structures; as a result of this, it has become necessary to maintain the environment of the manufacturing apparatus in a state of ultrahigh purity (that is to say, purity on the level of "ppt", or parts per trillion). As a result, in cases in which common gases of ultrahigh purity (for example, argon gas) are to be supplied through the medium of pipes which serve as gas flow conduits, it is necessary to determine, on the level of parts per trillion, the amount of impurities contained in the gas, such as moisture or the like, which adhere to the inner pipe surfaces, which comprise various materials.
Examples of conventionally known methods for the detection of adsorbed amounts include, for example, a method in which a microanalyzer (an atmospheric pressure ionization mass spectrometer) is connected to the pipe end of piping which is to be tested, a gas of ultrahigh purity is caused to flow into the piping from a gas purifier, and the amounts of impurities in the gas flowing out of the pipe end is measured.
However, in this conventional method, no account was taken of moisture which adhered to metal surfaces, and only the purity of the gas passing through the piping system which served as the gas conduit was measured, so that no precise determinations could be made with respect to the quality of the interior surfaces of the gas system.
The present invention was created in light of the abovedescribed problems in the conventional technology; it has as an object thereof to provide an evaluation method and an evaluation device for quantities of absorbed impurities which are capable of evaluating, on the order of parts per trillion, quantities of impurities contained in a gas which adsorb to a gas conduit comprising various materials.